A major impetus exists for the identification of structural brain anomalies in children with developmental disorders of higher cerebral function, to provide potential data on cerebral reorganization, as well as data upon which to base hypotheses regarding brain-behavior correlations in young children. In vivo evidence of structural anomalies may also demonstrate that some developmental abnormalities of higher cortical function reflect deviant brain organization rather than delayed maturation. A net computerized method of brain morphometry based upon high- resolution magnetic resonance imaging (MRI) is utilized in this project to provide an in vivo neuroanatomic evaluation of children prototypic for subtypes of developmental language disorders (DLD) and autistic spectrum disorders (ASD). Three analytic routines are applied to the MRI data for external validation of the behaviorally- and neuropsychologically-defined DLD and ASD: 1). Volumetric computation of whole brain and individual substructures; 2). Recognition of regional abnormalities of proton density as a function of signal intensity heterogeneity; 3). Geometric and shape characterization of brain structures and focal abnormalities. It is hypothesized that each subtype of DLD and ASD is characterized by a morphometrically distinguishable pattern of localized structural brain abnormality when compared to age- and sex-matched children with mental deficiency and control children with headaches. The prototypic abnormalities will be further correlated with the electrophysiologic and genetic characteristics defined by these respective projects.